Multipliable.h

// Mantid Repository : https://github.com/mantidproject/mantid
//
// Copyright © 2016 ISIS Rutherford Appleton Laboratory UKRI,
//   NScD Oak Ridge National Laboratory, European Spallation Source,
//   Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
// SPDX - License - Identifier: GPL - 3.0 +
#pragma once

#include "MantidHistogramData/DllConfig.h"

#include <algorithm>
#include <functional>
#include <stdexcept>
#include <type_traits>

namespace Mantid {
namespace HistogramData {
namespace detail {

/** Multipliable

  This class is an implementation detail of class like HistogramData::Counts and
  HistogramData::HistogramY. By inheriting from it, a type becomes multipliable,
  i.e., an object can be multiplied with another objects of the same type.

  @author Simon Heybrock
  @date 2016
*/
template <class T> class Multipliable {
public:
  /// Element-wise multiplication of this and other.
  T &operator*=(const T &other) & {
    auto &derived = static_cast<T &>(*this);
    checkLengths(derived, other);
    std::transform(derived.cbegin(), derived.cend(), other.begin(), derived.begin(), std::multiplies<double>());
    return derived;
  }

  /// Element-wise division of this and other.
  T &operator/=(const T &other) & {
    auto &derived = static_cast<T &>(*this);
    checkLengths(derived, other);
    std::transform(derived.cbegin(), derived.cend(), other.begin(), derived.begin(), std::divides<double>());
    return derived;
  }

  /// Element-wise multiplication of lhs and rhs.
  T operator*(T rhs) const {
    auto &derived = static_cast<const T &>(*this);
    return rhs *= derived;
  }

  /// Element-wise division of lhs and rhs.
  T operator/(const T &rhs) const {
    auto &derived = static_cast<const T &>(*this);
    T out(derived);
    return out /= rhs;
  }

protected:
  ~Multipliable() = default;

private:
  void checkLengths(const T &v1, const T &v2) {
    if (v1.size() != v2.size())
      throw std::runtime_error("Cannot multiply vectors, lengths must match");
  }
};

} // namespace detail
} // namespace HistogramData
} // namespace Mantid